Bobbin thread replenishing mechanism for lock stitch sewing machine



g- 6, 1963 R. E. JOHNSON ETA]. 3,099,972

BOBBIN THREAD REPLENISHING MECHANISM FOR LOCK STITCH SEWING MACHINEFiled Dec. 11, 1961 3 Sheets-Sheet 1 k0 Q w ,8 flu x N A a no 0 Y; 0 L0N g m x y I.

g D I 'I5I\;:V L 0%: g, INVENTORS. g 0 RALPH E. JOHNSON and 5 BY FRANKJ. BARTOSZ WITNESS IL :0"

WgL L ATTORJVE'Y 1963 R. E. JOHNSON ETAL 3,099,972

BOBBIN THREAD REPLENISHING MECHANISM FOR LOCK STITCH SEWINGMACHINE FiledDec. 11, 1961 I 5' Sheets-Sheet 2 v IDNVENTORS. RALPH E JOHNSON and .BYFRANK J. BARTOSZ WITNESS A g. 6, 1963 R. E. JOHNSON ETAL 3,099,972

BOBBIN THREAD REPLENISHING MECHANISM FOR LOCK STITCH SEWING MACHINE 3Sheets-Sheet 3 Filed Dec. 11, 1961 INVENTORS. RALPH E. JOHNSON and yFRANK J. BARTOSZ United States Patent F 3,099,972 BOBBIN THREADREPLENISEWG MECHANISM FOR LOCK STITCH SEWING MACHINE Ralph E. Johnson,Boonton, and Frank I. Bartosz, Cranford, N.J., assignors to The SingerCompany, a corporation of New Jersey Filed Dec. 11, 1961, Ser. No.158,451 8 Claims. (Cl. 112-181) This invention relates to lock stitchsewing machines of the type employing a loop taker rotatable in onedirection and referred to in the art as a rotary hook, and moreparticularly, to a novel and improved mechanism for replenishing thethread on a bobbin in place in a rotary hook.

It is an object of this invention to provide a novel and improvedmechanism for replenishing the thread on a bobbin in place in a rotaryhook during that interrelated motion of the needle and rotary hook as isrequired for the formation of lock stitches.

Another object of this invention is to provide a bobbin threadreplenishing mechanism of the above character employing stitch forminginstrurnentalities for producing lock stitches in the conventionalmanner and in which the means for effecting replenishment of the bobbinin place in the loop taker is physically separate from the stitchforming instrumentalities and remains both during bobbin replenishmentand conventional stitch formation out of physical engagement with anyelements of the stitch forming instrumentalities or the actuatingmechanism thereof.

With the above and other objects and advantages in view, as willhereinafter appear, this invention comprises the devices, combinations,and arrangements of parts hereinafter described and illustrated in theaccompanying drawings of a preferred embodiment in which:

FIG. 1 represents a side elevational view of a sewing machine with aportion of the bed broken away more clearly to illustrate this inventionapplied thereto,

FIG. 2 represents an enlarged end elevational view of the bed portion ofthe sewing machine of FIG. 1,

FIG. 3 represents an enlarged bottom plan view of the thread severingdevice of this invention including the operating bracket arm carried onthe pivoted bed extension,

FIG. 4 represents an enlarged end elevational view of the loop takerincluding fragments of the throat plate, presser foot, needle, and thethread deflector of the bobbin replenishing mechanism, and illustratesthe arrangement of parts and of the thread upon the initial 100p seizureat commencement of bobbin replenishment,

FIG. 5 represents a view similar to FIG. 4 illustrating the position ofparts and of the thread substantially at cast off of the initial loopseizure at the commencement of bobbin replenishment,

FIG. 6 represents a view similar to FIG. 4 illustrating the position ofparts and of the thread during seizure by the loop taker beak of thesecond loop after commencement of bobbin replenishment,

FIG. 7 represents a view similar to FIG. 4 illustrating, the position ofparts and of the thread substantially at cast off of the second loopseized by the loop taker after commencement of bobbin replenishment,

FIG. 8 represents a view similar to FIG. 4 illustrating 3,099,972Patented Aug. 6, 1963 the position of parts and of the thread uponcompletion of bobbin replenishment and in readiness for the formation oflock stitches, and

FIG. 9 is a cross sectional view of the loop taker including fragmentsof the thread deflector and thread severing knife taken substantiallyalong line 9-9 of FIG. 8.

Referring to the drawings, this invention may be embodied in aconventional lock stitch sewing machine having a bed 11, a standard 12,and a bracket arm 13: overhanging the bed. A needle 14 endwisereciprocable in the bracket arm is connected for cooperatinginterrelated motion required for the formation of lock stitches with a.loop taker indicated generally at 15 in the bed by means of a main shaft16 in the bracket arm, a standard shaft 17, connected to the main shaftby gears 18, and a bed shaft 19 connected to the standard shaft by gears20 and having the loop taker secured thereto. Any conventional workfeeding mechanism may be employed, as for instance, a drop feedmechanism including a feed dog 21 operating through a throat plate 22 onthe bed, which throat plate is also apertured as at 23 to accommodatethe needle. The bed may be provided with a bed extension 24 pivoted asat 25 to the bed.

As illustrated in FIG. 1, the needle thread is directed from a supplyspool 25 to the needle 14 by suitable guides and through a maintensioning device 28 of which all are conventional. The thread from theneedle eye to the supply spool will be hereinafter referred to as Twhile that limb of the needle thread extending from the needle to thefree extremity will be referred to as T The free extremity of thread T;in preparation for bobbin replenishment may be secured in a threadnipper 29 carried on the presser bar 30 to which the conventionalpresser foot 31 is supported.

Referring to FIGS. 2 and 4 to 9, the loop taker 15 preferably takes theform of a rotary hook including a cup shaped body portion 40 formed witha loop seizing beak 4-1. The body portion is formed with an internalraceway 42 complemented by a gib 43 to constrain therein a bearing rib44 of a bobbin case 45. The gib is formed with a thread detaining tail46.

The bobbin case 45 is formed with a center post 47 which is shoulderedas at 48 to accommodate a sleeve 49 of frictioning material such asnylon or other flexible synthetic plastic material. A bobbin 50 havingflanges 51 and 52 is journaled on the sleeve 49 for turning movementresisted only by the friction imposed by the sleeve 49. The center post47 of the bobbin case is transversely slotted as at 53 to accommodate aninturned lug 54 formed on a rotation restraining bracket 55 formed withan upwardly extending finger 56 disposed between spaced abutment springs57-57 secured beneath the throat plate 22. The rotation restrainingbracket 55 is maintained on the center post by the frictional engagementof the inturned lug 54 with the sleeve 49.

As thus far described, the rotary hook is capable of concatenating loopsof thread seized from the needle by the 'beak 41 completely about the:bobbin case and, of course, about the bobbin jour-naled therein so asto form lock stitches (Federal stitch type 301) when a locking or bobbinthread is present on the bobbin. This stitch forming process is of aconventional nature in which the seized needle thread loop entersbetween the loop taker 3 a body portion 40 and the bobbin case wthroughregistering gaps in the raceway 42 and bearing rib 44, caught againstthe so-called ingoing pocket, that is, one edge 58 of the bearing rib 44adjacent to the gap therein and thus divided into two limbs. The threadis then directed one limb between the bobbin case and the loop taker andthe other limb over the face of the bobbin and bobbin case, while thegaps move out of registry. Finally the thread is drawn out of the looptaker and up the finger 53 when the gaps again overlap.

For replenishing thread on the bobbin, this invention provides, asillustrated in FIGS. 1 and 2, a thread deflecting member 60 formed witha pair of obliquely inturned fingers 61 and 62. The member 60 is securedby a screw 63 to a plunger 64 slidable in a boss '65 in the bed with thefingers 61 and 62 disposed axially opposite the space between the bobbincase 45 and the periphery of the bobbin flange 51. The plunger 64 isformed with a head 66 con-straining on the plunger and against the bed acompression spring 67 which serves to bias the thread deflecting fingers60 and 61 into the space between the bobbin flange and the bobbin caseand within the space between the planes containing the bobbin flanges 51and 52 as illustrated in dotted lines in FIG. 9.

Pivoted at 68 in the bed is a bell crank having an arm 69 engaging theplunger head 66 and an arm 70 carrying a follower pin 71. A cam bracket72 secured beneath the bed extension plate 24 by screws 73 is tormedwith a cam finger 74 underlying the follower pin 71 and arranged so asto release the bell crank 70 when the bed extension plate 24 is raisedas illustrated in solid lines in FIG. 1 allowing the spring 67 to urgethe thread deflecting fingers opposite the space between the bobbinflanges, and arranged so as to turn the bell crank 69, 70 in a clockwisedirection as viewed in FIG. 1 when the bed extension is turned down intocoplanar relation with the bed 11 to force the plunger outwardly inopposition to the spring 67 and thus shift the thread deflecting fingersentirely outwardly beyond the face of the bobbin flange 51 asillustrated in solid lines in FIG. 9.

FIGS. 4 to 7 illustrate the manner in which the machine operates toreplenish bobbin thread when the bed extension plate 24 is raised. FIG.4 illustrates the position of the parts and of the needle thread shortlyafter initial loop seizure at commencement of bobbin replenishment. Thethread loop will next be caught in the ingoing pocket 58, divided andcarried one limb across the back and the other limb about the front ofthe bobbin case as illustrated in FIG. 5. The thread deflecting fingers60 and 61, however, being shifted to a position between the bobbinflanges will deflect the limb passing over the exposed face of thebobbin case inwardly and into the bobbin as illustrated in FIG. 5.

The second needle penetration after commencement of bobbinreplenishment, as illustrated in FIG. 6, will occur with a loop ofneedle thread detained about the bobbin. That limb of the thread on thebobbin which extends to the needle eye will pass behind a threadengaging finger -80 formed on the bobbin case and as the loop seizingbeak traverses that thread limb, which incidentally passes about thetail 46 of the gib, the second loop of needle thread drawn out by theloop seizing beak will extend between the needle and the thread engagingfinger 80. This second loop of thread will be caught in the ingoingpocket 58 and as shown in FIG. 7 and the divided loop will be carriedone limb behind and the other limb about the front face of the bobbincase. The thread deflecting fingers 60 and 61 will, as before, deflectthat limb passing over the exposed face of the bobbin case inwardly andinto the bobbin. As the thread loop illustrated in FIG. 7 is drawn oifthe loop taker, that portion caught in the thread engaging finger 80having passed about the back of the bobbin case will be drawn olf thethread engaging finger 80 and the thread will appear as in FIG. 6 exceptthat two successive loops of thread will be disposed on the bobbin. Thethread replenishing process can thus continue until any desired numberof successive loops of thread have been deflected onto the bobbin Withinthe capacity of the bobbin.

To terminate bobbin replenishment, it is only necessary that theoperator turn the bed extension 24 down into coplanar relation with thebed 11 as illustrated in dashed lines in FIG. 1. The cam finger 74 willthen urge the cam follower pin 71 upwardly, turning the lever 69, 70clock-wise as viewed in FIG. l and thereby urging the thread deflectingmember outwardly against the action of the compression spring 67 so asto position the thread deflecting fingers '61 and 62 outwardly beyondthe bobbin case and beyond the bobbin flange 5 1 as illustrated in solidlines in FIG. 9. On succeeding needle penetrations, therefore, the looptaker will concatenate seized loops of needle thread in the conventionalmanner completely about the bobbin and bobbin case so as to form lockedloops of needle and bobbin threads in the formation of lock stitches.

At the conclusion of bobbin replenishment two limbs of thread T and Twill extend from the bobbin and upwardly through the needle aperture 23and it is necessary that one of the limbs preferably T; be severedadjacent to the bobbin so that during subsequent stitching the thread onthe bobbin .can be drawn off as it is consumed in the seam.

The thread severing mechanism as illustrated in FIGS. 2 and 3, comprisesa bracket secured beneath the bed and on which is pivoted as at 911 aknife supporting lever 92 having secured at its free extremity a knifeblade 93 disposed axially opposite the body portion '40 of the looptaker. The knife supporting lever is biased by means of a wire spring 94which bears against a pin 95 on the lever 92 into a retracted positionagainst a stop provided by the head of a stop screw 96 in the bracket90. The retracted position of the lever 92 as illustrated in solid linesin FIG. 3 corresponds to the position of the blade 93 spaced outwardlybeyond the bobbin case as illustrated in solid lines in FIG.

Fulcrumed on the pin 95 is a U-shaped lever 97 slidably embracing theknife supporting lever and biased by means of a wire spring 98 toward aposition in which the base of U-shaped lever 97 strikes the knifesupporting lever 92. The U-shaped lever 97 carries a depending pin 99 bywhich the knife is shifted inwardly to sever the limb T of the thread onthe bobbin.

A bracket 100 secured by screws 101 to the bed extension 24 carries anupstanding pin 102 which moves, when: the bed extension is turned, in apath which intersects the pin 99 on the lever 97 when the lever 97 isbiased against the knife supporting lever 92.

When the bed extension is shifted from an upturned to a coplanarrelation with the bed, the pin 102 in engaging the pin 99 will shift theknife carrying lever 92 inwardly carrying the knife blade 93 toward theloop taker and into the position illustrated in dashed lines in FIGS. 3and 9 which as illustrated in FIG. 8 traverses the path of the threadlimb T and severs that thread limb.

The pin 102 in engaging the pin 99 will turn the knife supporting lever92 about the pivot pin 91 and the pin 99 in moving in an' are about thepin 91 will be turned out of the path of the pin 102 thus permitting thebed extension 24 to be turned into planar relation with the bed 11 andalso permitting the spring 94 to return the knife 93- outwardly beyondthe loop taker. When the bed extension 24 is next turned into anupstanding position, the pin 102 will contact the pin 99 and turn theU-shaped lever 97 against the action of the wire spring 98 until thearouate motion of the U-shaped lever 97 about the pin 95 moves the pin99 out of the path of the pin 102 thus allowing the bed extension to beturned up without disturbing the position of the knife supporting arm 92relatively to the head of the stop screw 96. i

The sewing machine described hereinabove thus provides means forreplenishing thread on the bobbin in place in the rotary hook duringthat interrelated motion of the needle and hook as is required for theformation of lock stitches. The machine will replenish bobbin threadwhenever and so long as the bed extension 24 is raised and upon loweringof the bed extension will sever the anchor limb of thread on the bobbinand automatically revert to lock stitch formation.

Having thus set forth the nature of this invention, what we claim hereinis:

1. In a sewing machine having a work penetrating thread carrying needle,a needle thread take-up member, a rotary hook, a thread engaging beak onsaid rotary hook, an annular internal raceway formed in said rotaryhook, a bobbin case, an annular bearing element on said bobbin casejournaled in said rotary book raceway, means for restraining said bobbincase from rotation with said rotary hook, said rotary hook raceway andsaid bobbin case bearing element each being formed with a gap, said gapsbeing disposed in registry in the needle loop seizing position of saidthread engaging beak, a thread accommodating bobbin formed with axiallyspaced flanges and journaled in said bobbin case, and actuating meansfor operating said needle, rotary hook, and take-up mechanism in timedrelation for seizure of loops of needle thread by said beak,manipulation of said seized thread loops through said registeringraceway and bearing member gaps and about said bobbin case by saidrotary hook, and shedding of said manipulated thread loop from said beakby said take-up member as is required in the formation of lock stitches,means for winding thread carried by said needle onto said bobbincomprising a thread deflecting finger, means supporting said finger onsaid sewing machine externally of said rotary hook, means for shiftingsaid thread deflecting finger into an effective position extendingopposite the space between said flanges of the bobbin journaled in saidbobbin case to deflect onto said bobbin thread loops shed from saidbeak, and means for maintaining said thread deflecting finger in saideffective position during a plurality of successive work penetrations ofsaid needle.

2. In a lock stitch sewing machine having a reciprocating threadcarrying needle, a loop-taker, a thread accommodating bobbin carriedwithin said loop-taker, and actuating mechanism operatively connectingsaid needle and said loop-taker for cooperative movement in timedrelation as is required for the seizure and manipulation by said looptaker of successive loops of thread from said needle, means forconstraining said bobbin within said loop-taker completely within thepath of a thread loop manipulated by said loop-taker, means supportedexternally of said loop-taker for deflecting successive loops of threadbeing manipulated by said loop-taker onto said bobbin while said bobbinis under the influence of said constraining means, means for sewing lockstitches using thread deflected onto said bobbin by said deflectingmeans comprising, means for rendering said deflecting means inefiective,and means for effecting termination of one limb of the last thread loopdeflected onto said bobbin at a point substantially within said looptaker.

3. In a sewing machine having a work penetrating thread carrying needle,a needle thread take-up member, a rotary hook journaled in said sewingmachine, a thread engaging beak on said rotary book, an annular internalraceway formed in said rotary hook, a bobbin case, an annular bearingelement on said bobbin case journaled in said rotary hook raceway, meansfor restraining said bobbin case from rotation with said rotary hook,said rotary hook raceway being formed with a gap into which said threadengaging beak extends, said bobbin case bearing element being formedwith a gap disposed in registry with said gap in said rotary hookraceway in the needle loop seizing position of said thread engagingbeak, a thread accommodating bobbin formed with axially spaced flangesand journaled in said bobbin case, and actuating means for operatingsaid needle, rotary hook, and take-up mechanism in timed relation forseizure of loops of needle thread by said beak, the manipulation of saidseized thread loops through said registering raceway and bearing membergaps and about said bobbin case by said rotary hook, and shedding ofsaid manipulated thread loop from said beak by said take-up member as isrequired in the formation of lock stitches, means for winding threadcarried by said needle onto said bobbin comprising a plunger axiallyslidable in said sewing machine along an axis substantially parallel tothat of said rotary hook, a thread deflector carried by said plunger, athread deflecting finger formed on said thread deflector and disposedoutwardly beyond the periphery of said bobbin flanges, operatorinfluenced means for shifting said plunger axially to position saidthread deflecting finger into and out of an effective position extendingopposite the space between said flanges of the bobbin journaled in saidbobbin case to deflect onto said bobbin thread loops shed from saidbeak, and means for maintaining said thread deflecting finger in saideffective position during a plurality of successive work penetrations ofsaid needle.

4. In a sewing machine as set forth in claim 3, a thread engaging fingerformed on said bobbin case and projecting into said gap in said bobbincase bearing element from that side of said gap toward which said threadengaging beak moves during rotation for engaging that limb of a threadloop deflected onto said bobbin which extends to and which is carried bythe needle into the path of the thread engaging beak of the rotary hookwhile said thread deflecting finger is maintained in said effectiveposition.

5. In a sewing machine as set forth in claim 3, a thread severing knife,means supporting said thread severing knife for movement in a pathintersecting one limb of a loop of thread shed from said thread engagingbeak and deflected onto said bobbin, and means operated by said operatorinfluenced means for shifting said knife into severing engagement withsaid thread limb when said thread deflecting finger is shifted out ofeffective position.

6. A sewing machine as set forth in claim 3, in which said operatorinfluenced means comprises a work support extension, means pivotallysupporting said work support extension on said sewing machine foroperator influenced movement into and out of an effective worksupporting position, and means carried by said work support extensionfor shifting said plunger to position said thread deflecting finger intoan effective position when said work supporting extension is moved outof an effective work supporting position.

7. A sewing machine as set forth in claim 3 in which said operatorinfluenced means comprises a work support extension, means pivotallysupporting said work support extension on said sewing machine foroperator influenced movement into and out of an effective worksupporting position, and means carried by said work support extensionfor shifting said plunger to position said thread deflecting finger intoan effective position when said work supporting extension is moved outof an eflective work supporting position, a thread severing knife means,means pivotally supporting said thread severing knife means relativelyto said sewing machine on an axis substantially perpendicular to thatdefined by said means pivotally supporting said work support extensionfor movement of said thread severing knife means in a path intersectingone limb of a loop of thread shed from said thread engaging beak anddeflected onto said bobbin, means biasing said thread severing knife ina retracted position out of engagement with said limb of said threadloop, a knife actuating drive pin carried by said work support extensionand disposed substantially perpendicular to the axis defined by saidmeans pivotally supporting said work support extension, a knifeactuating driven pin carried by said thread severing knife means anddisposed substantially parallel to the axis defined by said meanspivotally supporting said thread severing knife means, said drive pinbeing disposed relatively to said driven pin for operative engagementtherewith for shifting said thread severing knife into severing relationwith one limb of a loop of thread shed from said thread engaging beakand deflected onto said bobbin during operator influenced motion of saidwork support extension from uneffective to eifective work supportingposition.

8. A sewing machine as set forth in claim 7 in which a pivotal supportmeans .is provided for securing the driven pin to the thread severingknife means about an axis 10 substantially parallel to that defined bythe means for pivotally supporting the thread severing knife means rela-.tively to the sewing machine, and in which interengaging stop means areprovided between said thread severing knife means and saidpivotalsupport means for said driven pin for locking said driven pin relativelyto said thread severing knife means only during operative'engagement ofsaid 'drive pin with said driven pin during operator influenced motionof said work support extensions from uneffective to efiective Worksupporting position.

References Cited in the file of this patent UNITED STATES PATENTS1,794,255 Stephenson Feb. 24, 1931 FOREIGN PATENTS 1,224,744 France Feb.8, 1960

1. IN A SEWING MACHINE HAVING A WORK PENETRATING THREAD CARRYING NEEDLE,A NEEDLE THREAD TAKE-UP MEMBER, A ROTARY HOOK, A THREAD ENGAGING BEAK ONSAID ROTARY HOOK, AN ANNULAR INTERNAL RACEWAY FORMED IN SAID ROTARYHOOK, A BOBBIN CASE, AN ANNULAR BEARING ELEMENT ON SAID BOBBIN CASEJOURNALED IN SAID ROTARY HOOK RACEWAY, MEANS FOR RESTRAINING SAID BOBBINCASE FROM ROTATION WITH SAID ROTARY HOOK, SAID ROTARY HOOK RACEWAY ANDSAID BOBBIN CASE BEARING ELEMENT EACH BEING FORMED WITH A GAP, SAID GAPSBEING DISPOSED IN REGISTRY IN THE NEEDLE LOOP SEIZING POSITION OF SAIDTHREAD ENGAGING BEAK, A THREAD ACCOMMODATING BOBBIN FORMED WITH AXIALLYSPACED FLANGES AND JOURNALED IN SAID BOBBIN CASE, AND ACTUATING MEANSFOR OPERATING SAID NEEDLE, ROTARY HOOK, AND TAKE-UP MECHANISM IN TIMEDRELATION FOR SEIZURE OF LOOPS OF NEEDLE THREAD BY SAID BEAK,MANIPULATION OF SAID SEIZED THREAD LOOPS THROUGH SAID REGISTERINGRACEWAY AND BEARING MEMBER GAPS AND ABOUT SAID BOBBIN CASE BY SAIDROTARY HOOK, AND SHEDDING OF SAID MANIPULATED THREAD LOOP FROM SAID BEAKBY SAID TAKE-UP MEMBER AS IS REQUIRED IN THE FORMATION OF LOCK STITCHES,MEANS FOR WINDING THREAD CARRIED BY SAID NEEDLE ONTO SAID BOBBINCOMPRISING A THREAD DEFLECTING FINGER, MEANS SUPPORTING SAID FINGER ONSAID SEWING MACHINE EXTERNALLY OF SAID ROTARY HOOK, MEANS FOR SHIFTINGSAID THREAD DEFLECTING FINGER INTO AN EFFECTIVE POSITION EXTENDINGOPPOSITE THE SPACE BETWEEN SAID FLANGES OF THE BOBBIN JOURNALED IN SAIDBOBBIN CASE TO DEFLECT ONTO SAID BOBBIN THREAD LOOPS SHED FROM SAIDBEAK, AND MEANS FOR MAINTAINING SAID THREAD DEFLECTING FINGER IN SAIDEFFECTIVE POSITION DURING A PLURALITY OF SUCCESSIVE WORK PENETRATIONS OFSAID NEEDLE.